GSTT1 null genotype is a risk factor for diabetic retinopathy in
Caucasians with type 2 diabetes, whereas GSTM1 null genotype might confer
protection against retinopathy
Affiliations: Institute of Histology and Embryology, Medical Faculty
Ljubljana, University of Ljubljana, Ljubljana, Slovenia | Eye Clinic, University Medical Centre Ljubljana,
Ljubljana, Slovenia
Note: [] Corresponding author: Danijel Petrovič, MD, PhD, Institute
of Histology and Embryology, Medical Faculty of Ljubljana, Korytkova 2, 1105
Ljubljana, Slovenia. Tel.: +386 1 543 7367; Fax: +386 1 543 7361; E-mail:
[email protected]
Abstract: Aim: Substantial data indicate that oxidative stress is involved in
the development of diabetic retinopathy (DR). The aim of the present study was
to investigate whether the genetic polymorphisms: polymorphic deletions of
glutathione S-transferases M1 (GSTM1) and T1 (GSTT1) and Ile105Val of the GSTP1
are associated with DR in Slovenian patients with type 2 diabetes. Methods: In this cross sectional case-control study 604 unrelated Slovene
subjects (Caucasians) with type 2 diabetes mellitus were enrolled: 284 patients
with DR (cases) and the control group of 320 subjects with type 2 diabetes of
more than 10 years' duration who had no clinical signs of DR. Genotypes were
determined by polymerase chain reaction (PCR) and restriction fragment length
polymorphism (RFLP). Results: In our study, the deletion of the GSTM1 was
found less frequent in cases with DR than in the controls (27.5% versus
44.4%; P < 0.001), whereas the deletion of GSTT1 was found
significantly more often in cases than in the controls (49.3% versus
29.7%; P < 0.001). We did not find statistically significant
differences in the genotype distribution in GSTP1 (Ile105Val) polymorphism
between cases and controls (40.5% versus 46.0%). Conclusions: We may conclude that individuals homozygous for the deletion of GSTT1 are at an
≈ 2-fold-greater risk of DR, whereas the GSTM1 deficiency is associated
with lower frequency of DR in type 2 diabetics.
